(CIE A2 Biology) Stomata basics

an example of plants undergoing homeostasis

carbon dioxide constantly being supplied to mesophyll cells for photosynthesis

the purpose of the stomata and guard cells on leaves

to control gas diffusion in and out of leaves (eg. CO₂ enters leaves through these gaps)

the environmental stimuli that lead to stomatal apertures

increasing light intensity + low CO₂ concentration in the interleaf airspaces

the environmental stimuli that lead to stomatal closures

decreasing light intensity + high CO₂ concentration in the interleaf airspaces + low humidity + high temp. + high water stress levels from limited root water supplies/high transpiration rates

the main purpose of stomatal aperture regulation

to balance CO₂-uptake-by-diffusion reqs with a need to minimize transpiration-induced water losses

the main pro and con of leaving stomata open during daytime hours

the leaves will gain more CO₂ for photosynthesis but end up losing lots of water by transpiration

the main pro and con of leaving stomata closed during daytime hours

the leaves retain lots of water during periods of water stress but photosynthesize less due to lower CO₂ levels